Cloud Backup

This howto will describe a method for automatically backing up your funtoo install to the internet, in this case dropbox, but any online storage will do. Gentoo describes a method of creating a stage 4 archive. The problem with a stage 4 is that it is large and it archives a lot of unnecessary files. Such as applications that can be reinstalled from an emerge world. Instead, this method will aim for more of a "stage 3.5."

Note

This method does not attempt to backup everything. The intention is only to backup the system. Optionally you can also archive and copy your /home folder if you have enough online storage.

Use Case

A backup machine currently provides network drives on a home LAN to allow clients on the LAN to backup to, using apps such as Time Machine (Mac) and Genie Timeline (Windows). As this machine is the backup machine it doesn't have anywhere to backup to itself. In this situation a backup solution is provided by backing up to somewhere online - dropbox. If a restore from the backup is required, the client machine's backups would be trashed, and the backup machine restored.

Automatic Backup Archives With Etckeeper

Etckeeper is a tool that is used to save versions of /etc, including meta-data in a version control repository such as git.
As etckeeper is not in the funtoo portage tree, layman is used to provide an overlay.

Important

At the time of this writing, 13. October of 2014, the etckeeper ebuild is part of funtoo's portage tree. So you don't have to install it from an overlay but just emerge it.
As this ebuild comes from an unofficial source it is possible that it will not be existent, in which case you should follow the install instructions via layman

Install etckeeper via layman

Before you install layman it is worth mentioning that you probably want USE="git subversion" in /etc/portage/make.conf. After adjusting use flags, to install layman you run:

# emerge layman

In order to backup the layman configuration, but not the portage overlay trees, make the following modifications to the default install.
Tell Portage about layman-fetched repositories by adding the following line to /etc/portage/make.conf:

Encrypt Backups

It is a good idea to encrypt your backup before moving it online. This can be done with gpg, using a symmetric (password only) or public/private key encryption. Additionally you can chose to sign the backup to check its integrity before restoring.

# emerge gpg

Symmetric Encryption

There is no preparation required to use a symmetric key as all that is required is simply a passphrase. Just modify the cron job. Edit /etc/cron.daily/backup:

If you forget this password the backup will be unusable. Lose the password and you lose the backup.

As there is now sensitive information in this file, you might want to remove read permission:

# chmod og-r /etc/cron.daily/backup

Private/Public key Encryption

Make a private/public encryption/decryptions key pair. The public key will be used to encrypt and the private key to decrypt.

# gpg --gen-key

The public key is used to create the encrypted backup and needs to live on the computer being backed up. A copy of the private key needs to be made and stored securely in another place. If this machine becomes unbootable, and this is the only place the private key lives, the backup dies with it.
The private key should not be kept:

In the same place as the back up

On the machine being backed up

Note

The private key is the only key that will decrypt the backup. Lose this key and/or it's password and you lose the backup.

Replace "my-key" with the appropriate name from the key list. Also note the change from -c for symmetric encryption to -e for private/public key encryption.

Sign Backups

Create a 2nd private/public (signing) key pair. The private key is used to sign and the public key is used to check the authenticity/integrity.

# gpg --gen-key

Note

The password for this key will be required in the script below.

In this case the private key is required to sign the backup and the public key is used to check the integrity of the backup.
Follow a similar process as above to copy the public key to to another computer/storage media.

Download backup from dropbox

Log into your dropbox account and find your backup file. Move it to a public area if it isn't already in one. Then right click on it and click "copy public link."
Now on the computer to be restored, delete the contents of the /etc folder and download the backup file.

(Need to check if this needs done before chrooting into the new install).